More than 60 percent of all Internet traffic now comes from bots, according to a new study.

The study, published earlier this week by the web security firm Incapsula, found that online traffic from bots in 2013 — automated softwarethat include everything from hacking tools to spammers to search engine catalogers — is up 21 percent from 2012, when 51 percent of website visits already came from bots. Thirty-one percent of bots are malicious, according to the study, but spam bots decreased from two percent of traffic last year to half-a-percent in 2013.

The report includes evidence of more sophisticated hacker activity, including an eight percent increase in so-called “Other Impersonators,” hostile bots that attempt to impersonate benign bots and tend to be specifically crafted for a particular malicious activity.